<template>
  <!-- 商品分类导航 -->
  <div class="type-nav">
    <div class="container">
      <div @mouseleave="leaveShow" @mouseenter="show = true">
        <h2 class="all">全部商品分类</h2>
        <!-- 过渡动画 -->
        <transition name="sort">
          <!-- 三级联动 -->
          <div class="sort" v-show="show">
            <!-- 利用事件的委派+编程式导航实现路由的跳转与传递参数 -->
            <div class="all-sort-list2" @click.prevent="goSearch">
              <div class="item" v-for="(c1,index) in categoryList.slice(0,16)" :key="c1.categoryId"
                   :class="{cur:currentIndex==index}">
                <h3 @mouseenter="changeIndex(index)">
                  <a href="#" :data-categoryName="c1.categoryName"
                     :data-category1Id="c1.categoryId">{{c1.categoryName}}</a>
                </h3>
                <!-- 二级、三级分类 -->
                <div class="item-list clearfix" :style="{display:currentIndex==index?'block':'none'}">
                  <div class="subitem" v-for="c2 in c1.categoryChild" :key="c2.categoryId">
                    <dl class="fore">
                      <dt>
                        <a href="#" :data-categoryName="c2.categoryName" :data-category2Id="c2.categoryId">{{c2.categoryName}}</a>
                      </dt>
                      <dd>
                        <em v-for="c3 in c2.categoryChild" :key="c3.categoryChild">
                          <a href="#" :data-categoryName="c3.categoryName" :data-category3Id="c3.categoryId">{{c3.categoryName}}</a>
                        </em>
                      </dd>
                    </dl>
                  </div>
                </div>

              </div>
            </div>
          </div>
        </transition>
      </div>
      <nav class="nav">
        <a href="#">服装城</a>
        <a href="#">美妆馆</a>
        <a href="#">尚品汇超市</a>
        <a href="#">全球购</a>
        <a href="#">闪购</a>
        <a href="#">团购</a>
        <a href="#">有趣</a>
        <a href="#">秒杀</a>
      </nav>
    </div>
  </div>
</template>

<script>
  import {mapState} from 'vuex'
  import throttle from 'lodash/throttle'

  export default {
    name: 'TypeNav',
    data() {
      return {
        //存储用户鼠标移上哪一个一级分类
        currentIndex: -1,
        show: true
      }
    },
    //组件挂载完毕：可以向服务器发送请求
    mounted() {

      //当组件挂载完毕，让show属性变为false
      //如果不是Home路由组件，将TypeNav进行隐藏
      if (this.$route.path !== '/home') {
        this.show = false
      }
    },
    computed: {
      ...mapState({
        //右侧需要的是一个函数，当使用这个计算属性的时候，右侧函数会立即执行一次
        //注入一个参数state，其实即为大仓库中的数据
        categoryList(state) {
          return state.home.categoryList;
        }
      })
    },
    methods: {
      //动画显示
      changeIndex: throttle(function (index) {
        this.currentIndex = index;
      }, 40),

      //点击三级联动路由跳转
      goSearch(event) {
        //第一个问题：把子节点当中的a标签，加上自定义属性data-categoryName,其余子节点是没有的
        let element = event.target
        //节点中有一个属性dataset属性，可以获取节点的自定义属性与属性值
        let {categoryname, category1id, category2id, category3id} = element.dataset;
        //如果标签身上有categoryname一定是a标签
        if (categoryname) {
          //整理路由跳转的参数
          let location = {name: "search2"}
          let query = {categoryName: categoryname}
          //一级分类、二级分类、三级分类
          if (category1id) {
            query.category1Id = category1id
          } else if (category2id) {
            query.category2Id = category2id
          } else {
            query.category3Id = category3id
          }
          //判断：如果路由跳转的时候，带有params参数，捎带脚传递过去
          if(this.$route.params.keyword){
            location.params = this.$route.params
            //整理完参数
            location.query = query
            //路由跳转
            //location = {name:"search",query:{categoryName: categoryname,category1Id: category1id}}
            this.$router.push(location)
          }else{
            location.query = query
            //路由跳转
            //location = {name:"search",query:{categoryName: categoryname,category1Id: category1id}}
            this.$router.push(location)
          }
        }
      },

      //全部商品列表鼠标移除事件
      leaveShow() {
        this.currentIndex = -1
        if (this.$route.path !== '/home') {
          this.show = false
        }
      }

    }
  };
</script>

<style scoped lang="less">
  .type-nav {
    border-bottom: 2px solid #e1251b;

    .container {
      width: 1200px;
      margin: 0 auto;
      display: flex;
      position: relative;

      .all {
        width: 210px;
        height: 45px;
        background-color: #e1251b;
        line-height: 45px;
        text-align: center;
        color: #fff;
        font-size: 14px;
        font-weight: bold;
      }

      .nav {
        a {
          height: 45px;
          margin: 0 22px;
          line-height: 45px;
          font-size: 16px;
          color: #333;
        }
      }

      .sort {
        position: absolute;
        left: 0;
        top: 45px;
        width: 210px;
        height: 461px;
        position: absolute;
        background: #fafafa;
        z-index: 999;

        .all-sort-list2 {
          .item {
            h3 {
              line-height: 30px;
              font-size: 14px;
              font-weight: 400;
              overflow: hidden;
              padding: 0 20px;
              margin: 0;

              a {
                color: #333;
              }
            }

            .item-list {
              display: none;
              position: absolute;
              width: 734px;
              min-height: 460px;
              background: #f7f7f7;
              left: 210px;
              border: 1px solid #ddd;
              top: 0;
              z-index: 9999 !important;

              .subitem {
                float: left;
                width: 650px;
                padding: 0 4px 0 8px;

                dl {
                  border-top: 1px solid #eee;
                  padding: 6px 0;
                  overflow: hidden;
                  zoom: 1;

                  &.fore {
                    border-top: 0;
                  }

                  dt {
                    float: left;
                    width: 54px;
                    line-height: 22px;
                    text-align: right;
                    padding: 3px 6px 0 0;
                    font-weight: 700;
                  }

                  dd {
                    float: left;
                    width: 415px;
                    padding: 3px 0 0;
                    overflow: hidden;

                    em {
                      float: left;
                      height: 14px;
                      line-height: 14px;
                      padding: 0 8px;
                      margin-top: 5px;
                      border-left: 1px solid #ccc;
                    }
                  }
                }
              }
            }

            /*&:hover {*/
            /*  .item-list {*/
            /*    display: block;*/
            /*  }*/
            /*}*/
          }

          /*.item:hover {*/
          /*  background-color: skyblue;*/
          /*}*/

          .cur {
            background: skyblue;
          }
        }
      }

      //过渡动画的样式
      //过度动画开始状态（进入）
      .sort-enter {
        height: 0px;
      }

      //过渡动画结束状态（进入）
      .sort-enter-to {
        height: 461px;
      }

      //定义动画时间、速率
      .sort-enter-active {
        transition: all .5s linear;
      }
    }
  }
</style>
